Optical wavelength dispersion device and method of manufacturing the same

ABSTRACT

An optical wavelength dispersion device includes a first substrate; an input unit formed on the first substrate having a slit for receiving an optical signal; a grating formed on the first substrate for producing a first light beam form the optical signal for outputting; and a second substrate covered on the top of the input unit and the grating; wherein the input unit and the grating are formed from a photo-resist layer by high energy light source exposure.

CROSS REFERENCE OF RELATED APPLICATION

This is divisional application that claims the benefit of priority under35 U.S.C. §119 to a non-provisional application, application Ser. No.13/556,154, filed Jul. 23, 2012, which is a non-provisional applicationof a provisional application, application No. 61/557,387, filed Nov. 8,2011.

NOTICE OF COPYRIGHT

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to any reproduction by anyone of the patent disclosure, as itappears in the United States Patent and Trademark Office patent files orrecords, but otherwise reserves all copyright rights whatsoever.

BACKGROUND OF THE PRESENT INVENTION

1. Field of Invention

The present invention generally relates to a wavelength dispersiondevice, more particularly to an optical wavelength dispersion device ina SoC (system on chip) for reducing the size and cost of the device.

2. Description of Related Arts

Optical communication is any form of telecommunication that uses lightas the transmission medium. An optical communication system consists ofa transmitter, which encodes a message into an optical signal, achannel, which carries the signal to its destination, and a receiver,which reproduces the message from the received optical signal. Thereceiver comprises an input slit for receiving the optical signal, and agrating for splitting and diffracting the optical signal in differentdirections for outputting. In other optical applications, such asspectrometers or optical analyzers, the grating plays an important rolein the applications.

The by far leading technology for manufacturing MEMS devices isSi-micromachining with its various derivatives. However, manyapplications of microsystems have requirements on materials basis,geometry, aspect ratio, dimensions, shape, accuracy of microstructures,and number of parts that cannot be fulfilled easily by mainstreamsilicon-based micromachining technologies. LIGA, an alternativemicrofabrication process combining lithography, electro-plating andmolding, enables the high precision manufacture of microstructures withlarge structural height ranging from hundreds to thousands ofmicrometers thick. The yield of de-molding process in LIGA is not highenough for fabricating vertical grating due to the small pitches ofgrating structure.

U.S. Pat. No. 7,034,935 disclosed a high performance miniaturespectrometer with a detector array optically coupled to a slab waveguidestructure, a focal plane provided outside of the output face of the slabwaveguide structure. The detector array is mounted onto the slabwaveguide structure at a fixed distance from the output face on theoutput focal plane. Obviously, the size of the spectrometer in U.S. Pat.No. 7,034,935 is not effective because the structure of the spectrometeris assembled by a plurality of elements.

U.S. Pat. No. 7,485,869 disclosed an optical spectroscopy tool performedin the vacuum ultraviolet (VUV) region. However, the size of thespectroscopy in U.S. Pat. No. 7,485,869 is not effective because thestructure of the spectroscopy is assembled by a plurality of elements.

US2010053611 disclosed a diffraction grating structure having ultra-highdensity of grooves comprising an echellette substrate havingperiodically repeating recessed features, and a multi-layer stack ofmaterials disposed on the echellette substrate. The diffraction gratingis formed by semiconductor processes. However, it is not a SoCstructure.

According to the drawbacks aforementioned, the present inventionprovides an optical wavelength dispersion device and method ofmanufacturing the same for reducing the size and cost of the device.

SUMMARY OF THE PRESENT INVENTION

An objective of the present invention is to provide an opticalwavelength dispersion device with small size and lower cost.

Another objective of the present invention is to provide an opticalwavelength dispersion device in a SoC (system on chip) by high energylight source exposure.

For achieving the above objectives, the present invention is to providean optical wavelength dispersion device, comprising: a first substrate;an input unit formed on the first substrate having a slit for receivingan optical signal; a grating formed on the first substrate for producinga first light beam form the optical signal for outputting; and a secondsubstrate covered on the top of the input unit and the grating; whereinthe input unit and the grating are formed from a photo-resist layer by ahigh energy light source exposure; wherein the wavelength of the highenergy light source is from 0.01 to 100 nm.

According to the optical wavelength dispersion device aforementioned,wherein the high energy light source is selected from X-ray, soft X-rayor EUV.

According to the optical wavelength dispersion device aforementioned,wherein the width of the slit is from 5 to 500 μm.

According to the optical wavelength dispersion device aforementioned,wherein the grating has a concave, convex or planar profile with pitchesof laminar type, saw-tooth type, blaze type, sinusoidal type or acombination of those types.

According to the optical wavelength dispersion device aforementioned,wherein the first substrate and the second substrate are semiconductorsubstrates, glass substrates, metal substrates or plastic substrates.

According to the optical wavelength dispersion device aforementioned,further comprising an optical reflector formed on the first substratefor reflecting the first light beam from the grating.

According to the optical wavelength dispersion device aforementioned,wherein the optical reflector is formed from the photo-resist layer bythe high energy light source exposure.

Another embodiment of the present invention is to provide a method ofmanufacturing an optical wavelength dispersion device, the methodcomprising the following steps:

(a) providing a first substrate;

(b) forming a photo-resist layer on the first substrate;

(c) exposing the photo-resist layer by high energy light source througha high-energy-light-source mask, wherein the wavelength of the highenergy light source is from 0.01 to 100 nm;

(d) developing the photo-resist layer for forming an input unit with aslit and a grating;

(e) coating a reflective layer on the surface of the first substrate,the input unit and the grating; and

(f) covering a second substrate on the top of the input unit and thegrating.

According to the method of manufacturing an optical wavelengthdispersion device aforementioned, wherein the high energy light sourceis selected from X-ray, soft X-ray or EUV.

According to the method of manufacturing an optical wavelengthdispersion device aforementioned, wherein the width of the slit is from5 to 500 μm.

According to the method of manufacturing an optical wavelengthdispersion device aforementioned, wherein the grating has a concave ,convex or planar profile with pitches of laminar type, saw-tooth type,blaze type, sinusoidal type or a combination of those types.

According to the method of manufacturing an optical wavelengthdispersion device aforementioned, wherein the first substrate and thesecond substrate are semiconductor substrates, glass substrates, metalsubstrates or plastic substrates.

According to the method of manufacturing an optical wavelengthdispersion device aforementioned, wherein the thickness of thephoto-resist layer is from 10 to 1000 μm.

According to the method of manufacturing an optical wavelengthdispersion device aforementioned, wherein the high energy light sourcemask comprises a third substrate, a metal layer formed on the thirdsubstrate, metal patterns formed on the top of the metal layer and asilicon layer formed on the bottom of the third substrate.

According to the method of manufacturing an optical wavelengthdispersion device aforementioned, wherein the material of the thirdsubstrate is Si₃N₄ or SiC and the thickness of the third substrate isfrom 1 to 5 μm.

According to the method of manufacturing an optical wavelengthdispersion device aforementioned, wherein the metal layer is a Ti layerwith thickness from 10 to 200 nm and the metal patterns are Au patternswith a thickness from 1 to 10 μm.

According to the method of manufacturing an optical wavelengthdispersion device aforementioned, comprising the step after the step(c): rotating the high energy light source mask together with the firstsubstrate by a specified angle with respect to the beam direction of thehigh energy light source to form an optical reflector by a second timehigh energy light source exposure.

According to the method of manufacturing an optical wavelengthdispersion device aforementioned, further comprising the step after thestep (c): providing an optical reflector formed by a second time highenergy light source exposure through a photo-mask with a specified anglerotation opposite to the first substrate.

According to the method of manufacturing an optical wavelengthdispersion device aforementioned, further comprising the step of: hardbaking the input unit, the grating and the optical reflector withtemperature from 100 to 200° C.

According to the method of manufacturing an optical wavelengthdispersion device aforementioned, further comprising the step of:coating a high reflectivity coating layer on the surface of the firstsubstrate, the input unit, the grating and the optical reflector.

Other and further features, advantages and benefits of the inventionwill become apparent in the following description taken in conjunctionwith the following drawings. It is to be understood that the foregoinggeneral description and following detailed description are exemplary andexplanatory but are not to be restrictive of the invention. Theaccompanying drawings are incorporated in and constitute a part of thisapplication and, together with the description, serve to explain theprinciples of the invention in general terms. Like numerals refer tolike parts throughout the disclosure.

Additional advantages and features of the invention will become apparentfrom the description which follows, and may be realized by means of theinstrumentalities and combinations particular point out in the appendedclaims.

Still further objects and advantages will become apparent from aconsideration of the ensuing description and drawings.

These and other objectives, features, and advantages of the presentinvention will become apparent from the following detailed description,the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, spirits, and advantages of the preferred embodiments of thepresent invention will be readily understood by the accompanyingdrawings and detailed descriptions, wherein:

FIGS. 1( a) and 1(b) illustrate hint diagrams of the optical wavelengthdispersion device of the present invention.

FIG. 2( a) and FIG. 2( b) illustrate the top view and lateral view ofthe grating in FIGS. 1( a) and 1(b).

FIG. 3 to FIG. 9 illustrate processes for manufacturing the opticalwavelength dispersion device of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following description is disclosed to enable any person skilled inthe art to make and use the present invention. Preferred embodiments areprovided in the following description only as examples and modificationswill be apparent to those skilled in the art. The general principlesdefined in the following description would be applied to otherembodiments, alternatives, modifications, equivalents, and applicationswithout departing from the spirit and scope of the present invention.

For optical communication devices, basic elements, such as gratings, canbe made from silicon wafer but some cannot. Therefore, it is desirableto provide a method for fabricating the all elements of opticalcommunication devices by lithographic manufacturing processes.

Referring to FIG. 1, FIG. 1( a) illustrates a hint diagram of theoptical wavelength dispersion device of the present invention. Theoptical wavelength dispersion device 10 comprises a first substrate 11,an input unit 12 having a slit 121, a grating 13, an output unit (notshown) and a second substrate (not shown). The input unit 12 is formedon the first substrate 11 for receiving an optical signal through theslit 121. The width of the slit is about 5˜500 μm. The grating 13 isformed on the first substrate 11 for producing a first light beam(dispersed focused light beam) from the optical signal to the outputunit (not shown). The grating 13 has a concave, convex or planar profilewith pitches of laminar type, saw-tooth type, blaze type, sinusoidaltype or a combination of those types. Generally speaking, the opticalsignals of different wavelength are focused at different locations onthe output unit. The grating 13 is blazed to increase the diffractionefficiency of the specified diffraction order. The wavelength of theoptical signals is adaptable from 200 to 2000 nm. The output unit (notshown) is used for outputting the first light beam (dispersed focusedlight beam) from the grating 13. The external sensor (not shown)receives the first light beam from the grating 13 for afterwardprocessing. The second substrate (not shown) is covered on the top ofthe input unit 12 and the grating 13. Therefore, the space between thefirst substrate 11 and the second substrate (not shown) works as anoptical waveguide for receiving and transmitting optical signals.

Moreover, the input unit 12 and the grating 13 are formed from aphoto-resist layer by a high energy light source exposure. The highenergy light source can be X-ray, soft X-ray or EUV (extreme UV). Thewavelength of X-ray is from 0.01 to 1 nm, the wavelength of soft X-rayis from 0.1 to 10 nm, the wavelength of EUV is from 10 to 120 nm. Due tothe surface roughness limitation in optical telecommunications and localoptical communications, the wavelength with 0.1 to 1 nm of the highenergy light source is better than that with 1 to 100 nm. The firstsubstrate 11 and the second substrate 15 are semiconductor substrates,glass substrates, metal substrates or plastic substrates.

In FIG. 1( b), the optical wavelength dispersion device 10 furthercomprises an optical reflector 14 formed on the first substrate 11 forreflecting the first light beam from the grating 13. Thus, the externalsensor (not shown) can be positioned in any direction (especially inupper or lower side) near the optical wavelength dispersion device 10according to the user's designation. Also, the optical reflector 14 isformed from the photo-resist layer by high energy light source exposure.

FIG. 2( a) and FIG. 2( b) illustrate the top view and lateral view ofthe grating 13 in FIGS. 1( a) and 1(b). After the high energy lightsource exposure, the pitch between adjacent peaks of the grating isabout 3 μm and the surface roughness of the grating is about 5˜10 nm.Thus, the grating is suitable for using in both opticaltelecommunications and local optical communications.

FIG. 3 to FIG. 9 illustrate the processes for manufacturing the opticalwavelength dispersion device of the present invention. As shown, formanufacturing the optical dispersion device, first, a first substrate 11is provided and a photo-resist layer 111 with thickness about 10˜1000 μmis formed on the first substrate. All components of the opticalwavelength dispersion device will be formed from the photo-resist layer111, and the material of the photo-resist layer 111 is, for example,SU-8 or PMMA. Then, the photo-resist layer 111 is exposed by high energylight source 30, such as X-ray, soft X-ray or EUV (extreme UV), throughan high energy light source mask 20. The high energy light source mask20 comprises a substrate 201 (Si₃N₄ or SiC) with thickness about 1˜5 μm,a Ti layer 204 with thickness about 10˜200 nm formed on the substrate201, Au patterns 203 formed on the top of the Ti layer 204 and a siliconlayer 202 formed on the bottom of the substrate 201. A part of highenergy light source 30 is blocked by the Au patterns 203 with thicknessabout 1 to 10 μm, and the Au patterns 203 in the high energy lightsource mask 20 are transferred to the photo-resist layer 111 through ahigh energy light source exposure.

After the high energy light source exposure (for example), thephoto-resist layer 111 with high energy light source exposure area isdeveloped. After developing, the exposed area of the photo-resist layer111 forms an input unit 12 with a slit 121 (shown in FIG. 1) and agrating 13. Furthermore, an optical reflector 14 is formed by a secondtime high energy light source exposure through the high energy lightsource mask 20 with a specified angle rotation (for example, 45 degrees)before developing. Or the optical reflector 14 is formed by a secondtime high energy light source exposure with a photo-mask. Also, the highenergy light source mask 20 together with the first substrate 11 (shownin FIG. 4) should be rotated at a particular angle (for example, 45degree) during exposure. Or, the photo mask is rotated with a specifiedangle opposite to the first substrate during the second exposure forforming the second optical reflector. The photo mask could be theoriginal mask or another mask. For increasing the strength of the inputunit 12, the grating 13 and the optical reflector 14, the input unit 12,the grating 13 and the optical reflector 14 are hard baked withtemperature from 100 to 200° C.

Referring to FIG. 8, for increasing the reflectivity of the firstsubstrate 11, the input unit 12, the grating 13 and the opticalreflector 14, a high reflectivity coating layer (Au or Al) 112 is thencoated on the surface of the first substrate 11, the input unit 12, thegrating 13 and the optical reflector 14. Finally, a second substrate 15with high reflectivity coating layer (Au or Al) 112 is covered on thetop of the input unit 12 and the grating 13. Therefore, referring toFIG. 9, the space between the first substrate 11 and the secondsubstrate 15 works as an optical waveguide for the propagation of theoptical signals from the input unit 12 to the detector (not shown).

Moreover, not shown in FIG. 9, there are pluralities of first connectingunits formed on the first substrate 11 for combining with secondconnecting units formed on the second substrate 15. By the combinationof the first connecting units and the second connecting units, thestructure steadiness of the optical wavelength dispersion device 10 is,therefore, improved.

Although this invention has been disclosed and illustrated withreference to particular embodiments, the principles involved aresusceptible for use in numerous other embodiments that will be apparentto persons skilled in the art. This invention is, therefore, to belimited only as indicated by the scope of the appended claims.

One skilled in the art will understand that the embodiment of thepresent invention as shown in the drawings and described above isexemplary only and not intended to be limiting.

It will thus be seen that the objects of the present invention have beenfully and effectively accomplished. The embodiments have been shown anddescribed for the purposes of illustrating the functional and structuralprinciples of the present invention and is subject to change withoutdeparture from such principles. Therefore, this invention includes allmodifications encompassed within the spirit and scope of the followingclaims.

What is claimed is:
 1. A method of manufacturing an optical wavelengthdispersion device, the method comprising the steps of: (a) providing afirst substrate; (b) forming a photo-resist layer on said firstsubstrate; (c) exposing said photo-resist layer by high energy lightsource through a high-energy-light-source mask, wherein a wavelength ofsaid high energy light source is from 0.01 to 100 nm; (d) developingsaid photo-resist layer for forming an input unit with a slit and agrating; (e) coating a reflective layer on a surface of each of saidfirst substrate, said input unit and said grating; and (f) covering asecond substrate on top of said input unit and said grating.
 2. Themethod, as recited in claim 1, wherein said high energy light source isselected from a group consisting of X-ray, soft X-ray and EUV (extremeUV).
 3. The method, as recited in claim 1, wherein a width of said slitis from 5 to 500 μm.
 4. The method, as recited in claim 1, wherein saidgrating has a concave, convex or planar profile with pitches selectedfrom a group consisting of laminar type, saw-tooth type, blaze type,sinusoidal type and a combination of said laminar, saw-tooth, blaze, andsinusoidal types.
 5. The method, as recited in claim 2, wherein saidgrating has a concave, convex or planar profile with pitches selectedfrom a group consisting of laminar type, saw-tooth type, blaze type,sinusoidal type and a combination of said laminar, saw-tooth, blaze, andsinusoidal types.
 6. The method, as recited in claim 1, wherein each ofsaid first substrate and said second substrate is selected from a groupconsisting of semiconductor substrates, glass substrates, metalsubstrates and plastic substrates.
 7. The method, as recited in claim 5,wherein each of said first substrate and said second substrate isselected from a group consisting of semiconductor substrates, glasssubstrates, metal substrates and plastic substrates.
 8. The method, asrecited in claim 1, wherein a thickness of said photo-resist layer isfrom 10 to 1000 μm.
 9. The method, as recited in claim 1, wherein saidhigh energy light source mask comprises a third substrate, a metal layerformed on said third substrate, metal patterns formed on a top of saidmetal layer, and a silicon layer formed on a bottom of said thirdsubstrate.
 10. The method, as recited in claim 7, wherein said highenergy light source mask comprises a third substrate, a metal layerformed on said third substrate, metal patterns formed on a top of saidmetal layer, and a silicon layer formed on a bottom of said thirdsubstrate.
 11. The method, as recited in claim 9, wherein a material ofsaid third substrate is Si₃N₄ or SiC and a thickness of said thirdsubstrate is from 1 to 5 μm.
 12. The method, as recited in claim 10,wherein a material of said third substrate is Si₃N₄ or SiC and athickness of said third substrate is from 1 to 5 μm.
 13. The method, asrecited in claim 9, wherein said metal layer is a Ti layer withthickness from 10 to 200 nm, and said metal patterns are Au patternswith a thickness from 1 to 10 μm.
 14. The method, as recited in claim12, wherein said metal layer is a Ti layer with thickness from 10 to 200nm, and said metal patterns are Au patterns with a thickness from 1 to10 μm.
 15. The method, as recited in claim 1, after the step (c),further comprising a step of: rotating said high energy light sourcemask together with said first substrate by a specified angle withrespect to a beam direction of said high energy light source to form anoptical reflector by a second time high energy light source exposure.16. The method, as recited in claim 14, after the step (c), furthercomprising a step of: rotating said high energy light source masktogether with said first substrate by a specified angle with respect toa beam direction of said high energy light source to form an opticalreflector by a second time high energy light source exposure.
 17. Themethod, as recited in claim 1, after the step (c), further comprising astep of: providing an optical reflector formed by a second time highenergy light source exposure through a photo-mask with a specified anglerotation opposite to said first substrate.
 18. The method, as recited inclaim 14, after the step (c), further comprising a step of: providing anoptical reflector formed by a second time high energy light sourceexposure through a photo-mask with a specified angle rotation oppositeto said first substrate.
 19. The method, as recited in claim 15, furthercomprising a step of: hard baking the input unit, the grating and theoptical reflector with temperature from 100 to 200° C.
 20. The method,as recited in claim 15, further comprising a step of: coating a highreflectivity coating layer on said surface of each of said firstsubstrate, said input unit, said grating and said optical reflector.